Question

the crowd laughed at the clown change it into passive voice

Answer 1

the clown was laughed by the crowd.

Answer 2

The clown received the laughter from the crowd.

Here the subject is placed as object and the object is treated as subject but in no way the meaning of the sentence is altered.  

This is the regulation of English grammar that while altering a sentence in passive voice from active voice, verb and the sentence meaning will remain the same.